Automatic spending cuts are taking effect, at NASA and many other federal agencies, as the result of the failure by the White House and Congress to agree on a budget deal. Last month, NASA Administrator Charles Bolden told lawmakers that sequestration would reduce NASA's overall budget from the $17.8 billion that Congress approved last year to $16.9 billion.

Operational websites and social-media accounts were excluded from the suspension, however — which means existing Twitter accounts, including @NASA and @MarsCuriosity, can stay in business. NASA has rapidly expanded its online presence in the past couple of years, winning recognition from the Emmys, the Shorty Awards and the Webby Awards. Just this month, the Mars Curiosity mission's social-media team won the South by Southwest Interactive Award for best social-media campaign.

Waivers were also granted for mission announcements, media events and products, breaking-news activities and responses to media inquiries. In an emailed response to NBC News' inquiry, NASA spokesman Bob Jacobs said additional guidance would be issued next week, addressing areas that would be exempt from the suspension.

"It's important to point out that it's a suspension, not a cancellation," Jacobs wrote. "The agency's budget for the fiscal year is more that $1 billion below the original request. We are taking prudent steps to ensure the resources expended on outreach activities are done so wisely.

"Mission activities and much of the existing news and information dissemination is not likely to be impacted, including our successful social media efforts," he said. "However, it is important in this constrained fiscal environment to pause and assess how the money is being spent on a wide variety of outreach activities, many of which are funded by independent projects and programs. We are not canceling anything yet. We are being financially responsible by pausing long enough to review activities before they go forward."